1. Field of the Invention
The present invention relates to a method for producing a carbon sheet. The present invention also relates to a fuel cell separator.
2. Description of the Prior Art
A carbon sheet, especially a fuel cell separator, is conventionally produced by using, as the starting materials, a thermosetting resin, such as phenol resin or furan resin, and graphite powder and by using one of the following processes:
(1) The A component is shaped into the form of a sheet and then is cured and baked.
(2) The A component and the B component are blended together, are shaped into the form of a sheet, and are cured.
(3) The A component and the B component are blended together, are shaped into the form of a sheet, are cured, and then are baked.
The A component and the B component are the thermosetting resin and the graphite powder, respectively.
The electric conductivity of the product obtained by the method (2) is low.
It is difficult in the methods (1) and (3) to remove the volatile matter contained in the shaped bodies therefrom, and therefore the shaped bodies are liable to crack during the curing and baking steps, especially during the curing step. As a result, the yield is low in the methods (1) and (3). If the removal of the volatile matter is a low-level removal, crack formation can be prevented but the gas tightness of the product may be impaired.
Since baking is not carried out in the method (2), the method (2) is economically advantageous. However, the electric conductivity of the product is not sufficiently satisfactory for it to be used as fuel cell separators since the thermosetting resin is not carbonized.